Currently, it is common practice to detect or quantify distinct analytes using distinct detection or quantification techniques. For example, enzyme assays, immunoassays, chemical colorimetric assays, fluorescence labeling and measurement, chemiluminescent labeling and measurement, and electrochemiluminescent labeling and measurement, are a few exemplary well-known analytical techniques that may be used to detect the presence of various analytes. Many of these techniques are performed on a test strip or cartridge.
The test strips typically have specific zones or sites for testing located at various positions about the strip. Some of these strips contain an array of test sites for the multiple testing of a single analyte, or for the simultaneous testing of multiple analytes. Depending on the specific detection or quantification technique used, the test strips may or may not be used in combination with a separate measurement device. For example, where quantitative optical detection is required, an additional measurement device is also required to read the results of the test strip or cartridge. This is unlike the case with qualitative visual assays, for example, like those used in most over-the-counter pregnancy tests, where an observable color change on the test strip itself indicates the results of the test. Perhaps the best known example of a test strip used in combination with a separate device is a glucose test strip used in combination with a glucose meter.
However, independent of whether additional measurement devices are employed with the test strips, different detection and quantification techniques are not typically combined together. This is partly because each technique has a unique sensitivity, robustness, and tolerance. In addition, each technique typically has unique physical and chemical requirements. Further, it is often the case that the physical location of the test site read zones must be fixed or predetermined in order to enable a corresponding measurement device to read the test results. This is because the optical components within the measurement device are at a fixed location and the read zone must, therefore, be in a fixed location corresponding with the optical components so that a reading may be obtained (e.g., typical in most optically read glucose test strips).
In addition, the test sample dilution factor and detection system required to obtain the optimal testing conditions for one analyte are often incompatible with the dilution factor and detection system required for a second analyte. Thus, in order to test for both analytes, the user must either take multiple samples from the patient for use with different test strips, or draw one large sample for division into multiple samples so that the multiple samples may be used as different samples for different test strips. Requiring that multiple samples, or one large sample, be withdrawn is not only inconvenient for the patient, but can be painful as well, for example, when the sample is blood and it is withdrawn via venipuncture or multiple finger lances.
Therefore, running multiple tests on a single cartridge when multiple detection or quantification techniques are required or are desirable has heretofore been limited. Indeed, when the use of different techniques is required or desirable, the user most often employs multiple instruments, sometimes from multiple vendors, in order to obtain the test results. In the case where the user is a physician or laboratory technician, these devices can clutter and reduce the availability of highly valued bench space.
In addition, commercially available analytical devices are limited in that they either measure a single analyte or, if they can measure multiple analytes, require a large sample size. For example, the DCA 2000 system (Bayer Corporation, Diagnostics Division, Tarrytown, N.Y.) can measure hemoglobin A1c (“HbA1c”) using a very small sample (1 μL) of blood, but can only detect a single analyte on a single cartridge using a small volume. It is a one analyte per cartridge test. When the DCA 2000 is configured to detect more than one analyte on a single cartridge, the sample volume required is much larger. For example, a test to detect microalbumin and creatinine requires a 40-μL urine sample. Similarly, the Piccolo Point of Care Chemistry and Electrolyte System (Abaxis, Inc., Union City, Calif.) can run a panel of up to about 12 tests, but it requires 100 μL of a blood, plasma or serum sample.
Generally, commercially available analytical devices are also limited in that they are not capable of performing software updates (e.g., assay improvements or menu expansions) in a manner transparent to the user. Further, although some devices designed for point-of-care medical use perform automatic Quality Control (“QC”) checks, many ask the user to run control samples manually to assure accurate performance. The user is also asked to upload software or data for new assays, etc., manually. These operations require the user to have a more intimate knowledge of QC testing requirements and instrument maintenance than many potential users are willing or are able to acquire. In addition, devices without automatic update capabilities inevitably wind up obsolete as new tests, algorithms, and procedures are developed.
Accordingly, it would be desirable to have systems, devices, and cartridges capable of performing multiple tests on a single sample, using more than one detection or quantification technique. In addition, it would be desirable to provide cartridges and devices capable of performing these features using a small sample volume. It would also be desirable to have a device that provides automatic QC checks, updates, and data storage.
All patents, publications, journal articles, and other references cited herein are incorporated by reference in their entirety, as if each had been incorporated by reference individually.